SYDNEY (REUTERS) - Australia is offering a fourth dose of Covid-19 vaccines to its vulnerable groups from next month, federal health authorities announced on Friday (March 25), as a new Omicron strain races through the population.

The top advisory group on vaccines approved the fourth shot for vulnerable groups: those aged over 65, indigenous people over 50, people who are immunocompromised and care home residents.

On Thursday, Singapore said elderly people aged 80 and above, as well as those who have a weakened immune system or have severe chronic disease, would be eligible to receive a second booster dose for better protection against Covid-19.

Given the emerging international data on the waning of vaccine protection against severe disease over time, it is recommended that these groups of people get a second dose, Health Minister Ong Ye Kung said at a press conference by the multi-ministry task force tackling Covid-19.

Australia and Singapore join a list of countries where this option is also being considered or is already offered.

They include the following:

• Israel: Believed to be the first nation to make a fourth jab available from December 2021 and started a wide rollout in January this year.
• Chile: The first Latin American country to administer a fourth dose. People with weakened immune systems were be the first to receive the shots. The campaign was extended to all those over the age of 55 in February.
• Denmark: The country joined Israel and Chile in January to offer a fourth jab for people with a compromised immune system. It was also the first European country to do so.
• Hungary: The fourth dose started being offered in January as well to anyone who asks for it, after conferring with a doctor.
• Cambodia: High-risk groups started getting their fourth Covid-19 vaccine shots in January. The earlier rounds used Chinese-made vaccines, which were reported to have less efficacy, so the fourth round of high-priority vaccinations have used Cambodia's more limited supply of Pfizer vaccines.
• Thailand: The rollout of the fourth Covid-19 shots was ramped up in January to residents in its tourism-dependent regions. These included Bangkok, Phuket, Krabi and seven other provinces.
• South Korea: Fourth shots started being administered in February to those who live in nursing homes and care facilities, and others with declined immunisation, in light of a recent increase of infections among people aged 60 or older.

In Europe, countries including Britain and Sweden are offering the shots to immunocompromised and at-risk groups, including those in older age groups. Belgium and Poland have also authorised the jab for the immunocompromised.

US officials have previously said fourth doses would not be needed, though later said they are monitoring emerging data to evaluate the need for additional boosters.